This invention is related to manifolds and more specifically to a manifold system for use in a hydrocarbon storage system.
Current environmental regulations require the collection of the hydrocarbon vapors generated in a hydrocarbon storage facility at service stations in certain localities. One method of recovering these vapors when filling the tanks is to connect the vent lines from each tank to the top of the tank truck so that the vapors are displaced into the tank truck as the gasoline is flowing out of the tank truck into the underground tanks. One such system which performs this function includes a manifold to which the vent lines of each tank are connected and a vapor return line connecting the manifold to a surface location. Such a system is illustrated in the copending application entitled "Vapor Recovery System for Service Stations," Ser. No. 538,057, by Wagner and Brown, filed Jan. 2, 1975 now U.S. Pat. No. 3,915,205.
A manifold system for a hydrocarbon storage facility is desirable for several reasons. One basic reason is that the use of the manifold eliminates the need for more than one vent line. In the future, the vapors from a motor vehicle fuel tank will have to be collected and returned to the underground tanks. This is best accomplished by connecting the vehicle vapor return line to a manifold so that the pressures in each tank are equalized. Equalization of the tank pressures is especially important when gasoline from two tanks are blended and the vapors are to be collected. Use of a manifold also permits the easy addition of vapor recovery components to an existing system in a manner which usually eliminates the need for excavating down to each tank, thereby minimizing the possibility of damage and the costs.
A manifold which is designed to be used in a hydrocarbon storage system should have several characteristics. A system for isolating the vent lines from the tanks containing unleaded gasoline from the vent lines of the tanks which contain leaded gasoline is required to prevent contamination of the unleaded gasoline by the leaded gasoline. The manifold structure should permit easy access to the float valves for maintenance as well as easy removal of the float valves. A third consideration is the ability to seal off the vent line to one of the tanks so that it may be tested for leaks.